This invention relates to apparatus for forming a pack of the type comprising a contents-containing tray and a surrounding sleeve.
Packs of this sort are particularly used in the food industry for pre-prepared meals, for example microwaveable meals. Traditionally the food packer purchases a pre-manufactured sleeve, which is erected and the tray is then fed into it. This separate manufacture of the sleeves is expensive and the erecting and filling of the sleeves tends to be somewhat labour intensive.
Proposals have been made for forming such a pack by folding the sleeve around a tray, gluing one of the free edges and then bringing the free edges, or a stick flap on one of the free edges, together to form a sleeve around the tray. This presents certain conveying problems because the usual conveyor bed with upstanding moving lugs, cannot be used for the section of the machine in which the bottom of the sleeve needs to be swung upwardly to engage the stick flap on the other side wall. For this operation to happen the bed has to be substantially open and the solution to date has been to convey the pack through this section using a pair of dependent lugs which engage the trailing edge of the tray and sleeve. This arrangement allows for relative movement between the sleeve and tray in a manner which often results in sleeves being glued when they are not properly squared off, resulting in skewed sleeves. It can also be difficult to exert good downward pressure on the pack using this system and so gluing may be incomplete.
From one aspect the invention consists in apparatus for forming a pack comprising a contents-containing tray and a surrounding sleeve, the apparatus including conveying apparatus for conveying a tray along a path of travel, a plurality of stations disposed along said path, including a feed station for placing a foldable sheet, which defines a top, two side walls, a bottom and a flap attached respectively to said two side walls, onto the top of the tray, a first folding station for folding said side walls to lie adjacent the sides of the tray, a gluing station for gluing one or both of said flap and said bottom, and a second folding station for folding said bottom against said flap to engage the two together and complete the sleeve, characterised in that the second folding station includes drive means for engaging said side walls to drive the pack through the station whilst maintaining a predetermined spatial relationship between said side walls.
In a preferred embodiment said drive means fully support the pack for at least part of the travel through the second folding station.
It will be understood that by utilising the drive means to control the spatial relationship of the side walls, the sleeve can always be properly orientated when gluing occurs.
The drive means may comprise an independent drive element or elements for each drive wall such that the drive elements can be driven at different speeds to achieve the predetermined spatial relationship. In normal use, the respective speeds will be preset to suit a particular tray and sleeve combination, but sensors may be provided for achieving real time adjustments of the speeds.
It is particularly preferred that the drive means should be constituted by belts and that the belts may be inclined towards each other to support the pack.
In any of the above arrangements the apparatus may further include flexible pressure elements for exerting downward pressure on the pack as it passes through at least part of the second folding station. These flexible elements can not only enhance the gluing operation through added compression, they can also help to ensure that the packs are properly located onto the drive means and maintained in good driving relationship with the drive means. Preferably there are two sets of flexible pressure elements and the flexible elements may be adjustable both vertically and laterally with respect to the path of travel to allow for different pack sizes and the like. The flexible elements may be pivotally mounted to allow access to the path of travel.
From a second aspect the invention consists in an apparatus for forming a pack comprising a contents-containing tray and a surrounding sleeve, said apparatus including conveying apparatus for conveying a tray along a path of travel, a plurality of stations disposed along said path, including a feed station for placing a foldable sheet, which defines a top, two side walls and a bottom and a flap attached respectively to said two side walls, on the top of the tray, a first folding station for folding said side walls to lie adjacent the sides of the tray, a gluing station for gluing one or both of said flap and said bottom, and a second folding station for folding said bottom against said flap to engage the two together and complete the sleeve, characterised in that the second folding station includes a pair of opposed drive belts for drivingly engaging and supporting the pack.
The drive belts may be angled towards each other and one belt may be less deep than the other, to enable sleeves with a xe2x80x9cfootxe2x80x9d to be formed. Preferably the belts are independently driven.
In either of the above aspects of the invention belts have been specifically identified as the preferred form of drive means, but it is to be understood that rollers or chain and lug conveyers may provide at least some of the advantages of the specific embodiments and are incorporated within the invention.
From a still further aspect the invention consists in apparatus for forming a pack comprising a contents-containing tray and a surrounding sleeve, said apparatus including conveying apparatus for conveying a tray along a path of travel, a plurality of stations being disposed along said path, including a feed station for placing a foldable sheet, which defines a top, two side walls and a bottom and a flap attached to respectively to two side walls, on top of the tray, a first folding station for folding said side walls to lie adjacent the sides of the tray, a gluing station for gluing one or both of said flap and said bottom, and a second folding station for folding said bottom against said flap to engage the two together and complete the sleeve, characterised in that the second folding station includes flexible pressure elements for pushing downwardly on the pack.
The use of flexible pressure elements is particularly beneficial, because it prevents jamming or similar problems occurring, in those cases where the contents accidentally project above the top of the tray.
Although the invention has been defined above it is to be understood that it includes any inventive combination of the features set out above or in the following description.